The Lockheed Martin F-35B made its first flight on 11 June, piloted by BAE test pilot Graham Tomlinson. A former Royal Air Force pilot, Tomlinson flew the aircraft in conventional takeoff and landing modes from the Lockheed Martin facility at Fort Worth, Texas. Transition to short/vertical takeoffs and landings and hover flight will begin early next year.

The F-35B was the second Lightning II to begin flight tests, following the conventional takeoff and landing F-35A, which first flew on 15 December 2006. That aircraft has made more than 40 flights to date. The F-35B is the second of 19 development and demonstration aircraft. The next variant to fly will be the F-35C, configured for aircraft carrier operations.

F-35 deliveries are to begin in 2010 and continue well beyond 2030. The F-35/JSF program is one of the few Defense efforts that has the full endorsement of the Department of Defense, the military services, and the Congress.  

The F-35B STOVL variant will replace the AV-8B Harrier in U.S. Marine Corps squadrons, and GR (ground attack/reconnaissance) series Harriers aboard British aircraft carriers. Several other nations have "signed on" to the F-35B program, both for land-based operation as well as from existing and planned VSTOL carriers.

While the Harrier was inferior to most contemporary land-based fighter/attack aircraft, the F-35B will have the speed, electronics, and stealth characteristics of its land-based contemporaries. However, the F-35B will have a range of some 450 nautical miles on internal fuel compared to more than 600 nautical miles for the F-35A/C variants. 

In the United States the F-35B will be able to operate from the Navy's large amphibious ships of the LHA/LHD classes, which now operate detachments of Harrier STOVL aircraft. The later ships of these types are being specifically configured for F-35B operations.

To date the most negative aspect evident in the F-35/JSF program is the aircraft's designation. Then-Secretary of the Air Force James Roche designated the aircraft as the F-35 because the JSF technology demonstration aircraft was the X-35. That research aircraft was not even a prototype JSF, but a scale technology demonstrator. The situation would be like having designated the tilt-rotor MV-22 as the MV-15 because its technology demonstrator was the XV-15. 

According to the Department of Defense aircraft designation system, the next U.S. fighter aircraft should have been designated F-24. (The F-23 was the McDonnell Douglas competitive design to the Lockheed F-22 Raptor fighter.) The use of sequential numbers of each aircraft within a given category is spelled out in the official DoD instructions on aircraft designations. The instruction specifically states that the system "is mandatory for use by all DoD components."